Different from a conventional client/server mode, a P2P network does not have a central server node, and each node in the P2P network can not only serve as a server for providing services for other nodes, but also can receive services provided by other nodes that serve as servers. Thus, in the P2P network, each peer node is in an equivalent position, that is, each node is refereed to as an equivalent, or a peer.
During the implementation of the present invention, the inventor(s) found that, the prior art at least has the following problems The P2P network is a self-organized configuration network system. In the network, the behavior of joining the network or exiting the network performed by each peer is random. In the P2P network, each peer serves as a server for providing services for other peers, so that the random feature of the peers when joining or exiting the system may disturb the data transmission between nodes. For example, if another peer is connected to the current peer before the current peer gets offline and gets ready to download data from the current peer, but the current peer suddenly goes offline, on the one hand, the peer cannot serve as a server for providing the service for said another peer, and on the other hand, said another peer has to re-route to still another peer to obtain relevant data. The random feature of the online behavior of the peers may influence the normal operation of the network system, and may deteriorate the performance of the whole system. The influence caused by the random feature of the online behavior of the peers on the P2P network system is called a churn phenomenon.
Accordingly, corresponding measures need to be taken, so as to avoid as much as possible the negative effects on the system caused by the churn phenomenon, thereby enhancing the churn resistant capability of the P2P network.